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os1

[os] /ɒs/
noun, plural ossa
[os-uh] /ˈɒs ə/ (Show IPA)
1.
Anatomy, Zoology. a bone.
Origin of os1
1540-1550
Borrowed into English from Latin around 1540-50

os2

[os] /ɒs/
noun, plural ora
[awr-uh, ohr-uh] /ˈɔr ə, ˈoʊr ə/ (Show IPA)
1.
Anatomy, Zoology. a mouth or orifice of the body.
Origin
First recorded in 1730-40, os is from the Latin word ōs mouth

os3

[ohs] /oʊs/
noun, plural osar
[oh-sahr] /ˈoʊ sɑr/ (Show IPA)
1.
Geology. an esker, especially when of great length.
Origin
< Swedish ås (plural åsar) ridge

Os

1.
Symbol, Chemistry. osmium.

OS

1.
Old Saxon.
2.
Computers. operating system.

O, o

[oh] /oʊ/
noun, plural O's or Os; o's or os or oes.
1.
the fifteenth letter of the English alphabet, a vowel.
2.
any spoken sound represented by the letter O or o, as in box, note, short, or love .
3.
something having the shape of an O .
4.
a written or printed representation of the letter O or o.
5.
a device, as a printer's type, for reproducing the letter O or o.

O

[oh] /oʊ/
interjection
1.
(used before a name in direct address, especially in solemn or poetic language, to lend earnestness to an appeal):
Hear, O Israel!
2.
(used as an expression of surprise, pain, annoyance, longing, gladness, etc.)
noun, plural O's.
3.
the exclamation “O.”.
Origin
1125-75; Middle English < Old French < Latin ō
Can be confused
O, oh, owe.

o/s

1.
(of the calendar) Old Style.
2.
out of stock.
3.
(in banking) outstanding.

O/S

1.
(of the calendar) Old Style.

O.S.1

or o.s

1.
(in prescriptions) the left eye.
Origin
From the Latin word oculus sinister

O.S.2

1.
Old Saxon.
2.
Old School.
3.
Old series.
4.
(of the calendar) Old Style.
5.
Also, o.s. ordinary seaman.
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2017.
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British Dictionary definitions for os

os1

/ɒs/
noun (pl) ossa (ˈɒsə)
1.
(anatomy) the technical name for bone
Word Origin
C16: from Latin: bone; compare Greek osteon

os2

/ɒs/
noun (pl) ora (ˈɔːrə)
1.
(anatomy, zoology) a mouth or mouthlike part or opening
Word Origin
C18: from Latin

os3

/əʊs/
noun (pl) osar (ˈəʊsɑː)
1.
another name for esker
Word Origin
C19 osar (pl), from Swedish ås (sing) ridge

Os

Chemical symbol
1.
osmium

OS

abbreviation
1.
Old School
2.
Old Style (method of reckoning dates)
3.
Ordinary Seaman
4.
(in Britain) Ordnance Survey
5.
outsize
6.
Old Saxon (language)

o

/əʊ/
noun (pl) o's, O's, Os
1.
the 15th letter and fourth vowel of the modern English alphabet
2.
any of several speech sounds represented by this letter, in English as in code, pot, cow, move, or form
3.
another name for nought

o.s.

abbreviation
1.
out of stock
2.
(banking) outstanding

O1

symbol
1.
(chem) oxygen
2.
a human blood type of the ABO group See universal donor
3.
(logic) a particular negative categorial proposition, such as some men are not married: often symbolized as SoP Compare A, E, I2
abbreviation
4.
(Austral, slang) offence
Word Origin
(for sense 3) from Latin (neg)o I deny

O2

/əʊ/
interjection
1.
a variant spelling of oh
2.
an exclamation introducing an invocation, entreaty, wish, etc: O God!, O for the wings of a dove!
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for os

o

interjection of fear, surprise, admiration, etc.; see oh.

O

blood type, 1926, originally "zero," denoting absence of A and B agglutinogens.

Online Etymology Dictionary, © 2010 Douglas Harper
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os in Medicine

os 1 (ŏs)
n. pl. o·ra (ôr'ə)

  1. An opening into a hollow organ or canal.

  2. The oral cavity; mouth.

os 2 (ŏs)
n. pl. os·sa (ŏs'ə)
Bone.

Os
The symbol for the element osmium.

OS abbr.
Latin oculus sinister (left eye)

o
The Greek letter omicron. Entries beginning with this character are alphabetized under omicron.

O 1

The symbol for the element oxygen.

O 2
abbr.
oculus

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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os in Science
Os  
The symbol for osmium.
O  
The symbol for oxygen.
osmium
  (ŏz'mē-əm)   
Symbol Os
A hard, brittle, bluish-white metallic element that is the densest naturally occurring element. It is used to make very hard alloys for fountain pen points, electrical contacts, and instrument pivots. Atomic number 76; atomic weight 190.2; melting point 3,000°C; boiling point 5,000°C; specific gravity 22.57; valence 2, 3, 4, 8. See Periodic Table.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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